Various methods of labels and tags have been used to identify assets, particularly to track items in transit or as they are being purchased by a consumer, including for example, Uniform Product Codes (“UPC”), Serialized Shipping Container Codes (“SSCC”), International Standard Book Numbers (“ISBN”), magnetic cards, integrated circuit (“IC”) cards, and radio frequency identification (“RFID”) tags. These tags, when read and translated, identify some property of the asset which may be used to track, collate, manage or convey the assets in the asset management system. The identification data may be stored in a private format, but to improve interoperability, the EPCglobal organization (Electronic Product Code organization) has developed a standard format for the RFID numbers.
As shown in FIG. 1, the electronic product codes (“EPC”) 500 are typically 96 bits wide and include a version number 502, a manager number 504 that identifies the producer of the asset, an object class 506 that identifies the type of asset (such as a SKU), and a serial number 508 that distinguishes each individual tag. In addition to the 96-bit EPC, various other EPC formats have been proposed including a 256-bit EPC. The EPC is typically stored on a RFID tag 514 (shown in FIG. 2) including a microchip or IC with an attached antenna.
To resolve the EPC into product information, the reader 510 sends a radio frequency signal 512 querying any identification tags 514 in range, as shown in FIG. 2. An active identification (“ID”) tag 514a has a battery to run the IC to broadcast a reply to the reader, and a passive tag 514b draws power from the sent signal 512 to reply. Either reply 518 to the reader will include the tag's EPC 500a, 500b. The reader then communicates with a Savant computer system 516, which is a form of distributed software specified by the Massachusetts Institute of Technology Auto-ID Center (now a part of EPCglobal). The reader may be physically connected to the Savant computer and/or may be a mobile reader which communicates with the Savant computer system either through a wireless connection, such as “Wi-Fi” or may download a batch of received EPC's when physically attached to the Savant computer system and/or the network, such as through a docking station. The Savant computer system sends the received EPCs 500a, 500b to an Object Name Service 524. The Object Name Service 524 then returns an address 520a, 520b for a Product Markup Language (“PML”) server 526 containing asset information 522 for each given EPC. Using the received address, the Savant computer system may contact the PML server 526 to retrieve and/or update the asset information 522.
Simple ID tags may only be able to send the stored identification data and perhaps receive one or two commands such as “awaken” or “erase stored identification data.” More complex tags, although more expensive, can perform many functions, including encryption or authorization checks, writing memory blocks, calibrating sensors, and/or making measurements. The communications 530 between the ID tags and reader are generally through a private protocol idiosyncratic to the tag manufacturer.